[SQL] Time related question...

I have a database that tracks the service calls we do.  In the database
are abstime values for:
  dateentered
  dateclosed
  dateassigned
  datecontacted

I have perl scripts managing the interaction between our web site and the
database.

My question is: what is the SQL statement that will allow me to find:
  1) a list of the calls where the difference between the dateentered and
  dateclosed is less than (say) 3 days.

I have tried:
  Select * from servicecall where (dateentered <#> dateclosed) #<= 3 days;
  Select * from servicecall where (dateclosed  - dateentered) #<= 3 days;
  Select * from servicecall where (dateentered <#> dateclosed) #<= @3 days;
  Select * from servicecall where (dateclosed  - dateentered) #<= @3 days;

Any suggestions?

Thanks.

--

        Kevin Colagio, Systems Administrator, Webmaster,
                      and perpetual student.
                   kcolagio@wc.eso.mc.xerox.com
           Personal URL:<http://www.rit.edu/~kdc5072>